The RHS have a series of reference books - you may find the garden centre already has some of them to use as a reference - many do. Two very useful ones are The A-Z of garden plants and the Encyclopedia of gardening. Basically the first one describes the plants and the second one how and where to grow them.
They aren't cheap but they will answer most questions.
It sounds as though the second one might be most useful to begin with perhaps.

Hi Moth as you work at the GC it is to be expected that customers will ask you a lot of questions. You might want to ask your employer to send you on some courses so that you at least have a basic idea of things. One very important point if a customer does ask you a question and you don'r know the answer please don't fudge... refer them to someone who does know or simply apologise and say you are new and aren't sure. I don't envy you starting work at a GC if you have very little knowledge of plants and growing needs.

If the garden centre has wifi, the best thing you can do is use your smartphone to google whichever plant it is, using the full Latin name and adding 'growing conditions UK' to the search - that should throw up some useful links with information. If, that is, your manager doesn't mind your doing that - in my own experience, managers at garden centres will keep you busy the whole day with unloading, reloading, repotting, display arrangements, watering and a host of other tasks. They may not like you taking time to help customers with information... sad, but true....

Gosh...talk about in at the deep end Moth! I agree with above...don't fudge it, get someone else who knows to help the customers while you learn. Nobody will mind if you are honest. I learned loads when I started from the RHS Encyclopedia of Plants and Flowers. But most of my knowledge has come from gardening and watching TV Gardeners. Do you have a garden of your own? I hope you enjoy your job though....and learn lots through working there :)

I don't know your location, but I find a wealth of knowledge and wisdom from attending courses/forums/exhibits at the New York & Brooklyn Botanical Gardens. Many lectures are posted online. You can also glean knowledge here just from reading the comments & reading the blogs & developing relationships with members. As stated above, watching documentaries, TV & Radio gardening shows also help. Many questions are repetitive & only require a basic knowledge. Your knowledge will grow as you immerse yourself in the subject.

I think that the term that Bathgate has used, ''Your knowledge will grow'' is the most important thing that you should hold on to. Unfortunately, GCs want to employ staff with a good knowledge of horticulture but want to pay as little as possible. Yes, don't be afraid to say that you don't know but try and find an experienced member of staff to whom you can refer to. Unlike lots of work environments, in horticulture, most people are so willing to share their knowledge with others. You will also come across the customers who will ask you questions to which they already know the answer to. You will get over them. Good luck.

welcome to GoY and well done on getting the Job.

I'd also recommend the RHS books mentioned, but they are big heavy books. ask if there are any reference books used by the gc already. and if not see if they will buy some. the dr hesayon 'expert' books are also decent. the flower and shrub book would be the most useful. the info is mainly the most commonly grown plants.

as a customer I often 'chip in' when I here some one ask and if the employee doesn't know. So don't worry you will pick it as you go. but don't make it up please.

Welcome to Goy Moth and congratulations on landing the job. If your employer is helpful explain your lack of knowledge and discuss with him/her how you can learn more. When I started gardening as an amateur/owner I was totally clueless. Dougal Philip who owns our local GC was very helpful and advised me to buy the Dr Hessayon series of books. You may be able to buy copies in charity shops for very little. They are very basic but explain as much as your customers are likely to need in the way of information. The RHS books are great if you can afford them, maybe the GC has copies which you can access to help customers. More knowledgeable staff may have tucked them under the counter as surplus to their needs. When I apologised to Dougal for my endless questions he assured me the only fool was the one who can't bring himself to ask for fear of showing his ignorance. Enjoy your new job and come back asking questions as often as you like. Some of our members are professional gardeners but the majority are keen amateurs with years of experience between them in growing all kinds of plants from annuals to vegetables. One question you are likely to be asked at this time of year is 'is it safe to plant now, the annual plants offered for sale' Be sure to tell them it is too early to plant in the open garden because of the danger from frost (until the end of May in some parts of the UK.) It is fine to plant up pots etc as long as there is somewhere to keep them safe.

Blimey, my local Wyevale wouldn't thank you for telling customers they shouldn't plant their bedding out now, Scotsgran - half their profit comes from people planting stuff out, having it die, then coming back for more later on. Easter weekend is the busiest for all garden centres, and most of what people buy is bedding. The big chain garden centres aren't usually very informative, quite deliberately... they are commercial emporiums more than proper plant people, though in my experience, our local Wyevale is one of the worst for that. I remember when our Wyevale was owned by someone else, and was more of a plant nursery and garden centre, when you could still buy a hardy fuchsia in winter, and get good advice. Go there now in December and all you'll find outside is christmas trees and wreaths. I rue the passing of the original plant nurseries, they used to be everywhere.

Well if Moth is ever going to learn he ought to learn that a satisfied customer does come back. Maybe people buy from supermarkets rather than GC's because they have found out that planting twice is very expensive. Garden centre annuals usually cost at least twice as much as the cheap supermarkets and folk do learn quite quickly. We are lucky to be members of the SRGC or AGS because both invite traders to their shows where we can buy plants at what would be described as reasonable prices. Honest advice is given freely and I have yet to find any dissatisfied customers.

With so much to know on this subject it is important to know what you don't have to know. If you are asked a question and you have no idea of the answer of course refer them to some source for their inquiry but make a note of that question or questions and find the answer for yourself preferably after your job on the web. Soon, you will find that most of the questions the customers will ask you will be repetitive and of course you will be ready with the answer. With a part time job at a GC there is no need to take immersion courses on your own time for this unless this job has sparked a new found personal interest in this subject. Your employer hired you and was satisfied with what knowledge you had but I truly hope that it is realized that you have the quality of being a conscientious employee.

Thank you so much to you all for your considered & helpful answers. The time you have taken is much appreciated, as is all your encouragement. I have borrowed a couple of the Dr Hessayon books and they are great. Three shifts in and all is well.

Yeah Moth! Enjoy!

Glad to hear you are finding gardening so enjoyable.